| 1-2-3 block |
A precise metal block with dimensions measuring one, two, and three inches respectively. An operator can use a 1-2-3 block to touch off tools during setup. |
| center finding indicator |
A measuring instrument that allows an operator to find the center of a hole on a part. |
| cutter compensation |
An offset used on the mill that accounts for variations in tool diameter. Cutter compensation is necessary only for tools that travel in the X- or Y-axis. |
| dial indicator |
A measuring instrument with a contact point attached to a spindle and gears that moves a pointer on the dial. Dial indicators have graduations that are available for reading different measurement values. |
| edge finder |
A device used on a mill to locate the exact position of a part edge along the X-axis or Y-axis. |
| flange |
A ring or collar surrounding the toolholder that allows the tool to be grasped by the toolchanger. |
| G28 |
The command code that defines program zero in a part program. |
| G30 |
The command code that places the X- and Y-axes in a temporary home position. |
| gage line |
The imaginary line marking the portion of the toolholder that matches the bottom edge of the machine spindle. |
| job sheet |
A document that includes all manufacturing specifications for a lot of parts. |
| machine coordinate system |
An unchangeable coordinate system that has machine zero as its origin. |
| machine zero |
The position located at the farthest possible distance in a positive direction along the machine axes. This position is permanently set for each particular CNC machine. |
| manual reference position return |
A procedure for returning a tool to a position specified by a parameter. The manual reference position return switch is located on the machine operator's panel. |
| part program |
A series of instructions used by a CNC machine to perform the necessary sequence of operations to machine a specific workpiece. |
| program zero |
The position that acts as the origin for the part program of a particular workpiece. This position is unique to each workpiece design, and it is selected by the part programmer. |
| reference plane |
A surface chosen for touching off all tools on a mill. A reference plane can be defined relative to a vise, fixture, or object like a 1-2-3 block. |
| tool length offset |
An offset used on the mill that accounts for variations in tool length along the Z-axis. Each tool requires its own offset, which is measured from the tip of the tool to the gage line. |
| work coordinate system |
A variable coordinate system that has program zero as its origin. |
| work offset |
An offset used to adjust the location of every tool loaded in the machine. On the mill, the work offset changes the position of the spindle in both the X- and Y-axes, and often the Z-axis as well. |